header_filter_by_lua --------------- **语法：** *header_filter_by_lua &lt;lua-script-str&gt;* **环境：** *http, server, location, location if* **阶段：** *output-header-filter* 用`<lua-script-str>`中指名的lua代码，来完成应答消息头部的过滤。 注意，下列的接口函数在这个执行阶段是被禁用的： - 输出类函数（例：ngx.say 和 ngx.send_headers） - 控制类函数（例：ngx.redirect 和 ngx.exec） - 子请求相关函数（例：ngx.location.capture和ngx.location.capture_multi） - cosocket 类函数（例：ngx.socket.tcp 和 ngx.req.socket） 这里有个使用 Lua 过滤完成覆盖应答头的例子（如果没有则添加）： ```nginx location / { proxy_pass http://mybackend; header_filter_by_lua 'ngx.header.Foo = "blah"'; } ``` 该指令在版本 `v0.2.1rc20` 中第一次引入。 [返回目录](#directives) > English Source **syntax:** *header_filter_by_lua &lt;lua-script-str&gt;* **context:** *http, server, location, location if* **phase:** *output-header-filter* Uses Lua code specified in `<lua-script-str>` to define an output header filter. Note that the following API functions are currently disabled within this context: - Output API functions (e.g., ngx.say and ngx.send_headers) - Control API functions (e.g., ngx.redirect and ngx.exec) - Subrequest API functions (e.g., ngx.location.capture and ngx.location.capture_multi) - Cosocket API functions (e.g., ngx.socket.tcp and ngx.req.socket). Here is an example of overriding a response header (or adding one if absent) in our Lua header filter: ```nginx location / { proxy_pass http://mybackend; header_filter_by_lua 'ngx.header.Foo = "blah"'; } ``` This directive was first introduced in the `v0.2.1rc20` release. [BACK TO TOC](#directives)